The horrific death of Young & Rubicam executive Suzanne Hart in a jinxed elevator at 285 Madison Ave. raises a big question beyond the tragedy’s specific cause.

Namely: What’s a great advertising agency, a name synonymous with “Madison Avenue,” doing at an antiquated 1925 property unsuited to modern commercial use?

The answer: Lots of companies in New York work out of creaky, obsolescent buildings put up more than 50 years ago. The biggest reason is the scarcity of newer ones — an imbalance that severely limits options for businesses wanting to move.

If ever there was an argument for new commercial construction — despite whiners who venerate pre-World War II Manhattan — it’s the prevalence of lousy buildings like 285 Madison.

Office workers there told The Post they found its violations-prone elevators “creaky and scary.” No one yet knows whether the challenge of maintaining an 86-year-old building contributed to this week’s nightmare. But it’s a scary reminder that Manhattan’s office stock, engine of the state’s economy, is woefully dated compared with other world capitals.

Despite a handful of glamorous projects like One Bryant Park and One World Trade Center, very few new towers have been built here in recent decades — thanks to political and economic challenges that stunt development.

As real-estate company CBRE’s regional CEO, Mary Ann Tighe, first trumpeted, an astounding 65 percent of the island’s office buildings are at least 50 years old.

Heavily concentrated in the Wall Street area and the West 30s and 40s, they’re cursed with awkward floor plates, small windows and infrastructure pitiably unsuited to the digital age.

Those which haven’t been expensively modernized top to bottom or converted to apartments face a gloomy future, and guarantee a miserable present for current tenants — like Y&R, which has occupied 285 Madison since 1926.

Y&R long wanted out of there, and last month signed up for modern space at 3 Columbus Circle, where it will move in 2013.

So why did Y&R stay so long? One big reason was the relative scarcity of affordable newer places to go. Recent vacancy rates of plus or minus 10 percent are misleading. Most available space is in older buildings; vacancies in more contemporary ones, even those built after 1960, are in the single digits.

By limiting companies’ moving options, the modern-space shortage encourages staying put. Of course, it also drives up relocation costs. Although office space isn’t subject to rent-regulation laws as apartments are, the law of supply and demand still applies.

No other world capital has anything like New York’s antique office stock. Shanghai’s business districts are mostly brand new. In London, an office market with barely half of Manhattan’s 400-odd million square feet, 57 million square feet in new buildings have come on line in the last 10 years, according to CBRE — versus under 10 million in Manhattan.

No wonder Tighe recently said that as she flew home from China, the sight of the Manhattan skyline made her think, “What a romantic 20th-century city.”

It was affectionate but cautionary, too — a reminder of how locked in the past we’ve become. And while Y&R is at last getting out (tragically too late for Suzanne Hart), too many other firms are still trapped.